Circuit interrupting apparatus



Sept. 24, 1940. c. vP. WEST 2,215,804

CIRCUIT INTERRUPTING APPARATUS Filed June 30, 1938 2 Sheets-Sheetl Phase74 J77zfter 7/ g Q a3 WITNESSES: INVENTOR w 67707165 1. W552i Sept. 24,1940. W T 2,215,804

' CIRCUIT INTERRUPTING APPARATUS Filed June 30,' 1938 '2 Sheets-Sheet 2WITNESSES:

Y INVENTOR- Charles P. West.

Patented Sept. 24, 1M0

more!) s'r rss CIRCUIT INTERRUPTENG APPARATUS Uharles P. West, ForestHills, LPa., assignor to Westinghouse Electric & Manufacturing Company,East Pittsburgh, Pa, a corporation of Pennsylvania Application June 30,1938Serial No. 216,701

15 Claims.

My invention relates to circuit-interrupting systems and it hasparticular relation to are interrupting systems utilizing electricdischarge apparatus.

It is an object of my invention to provide an arc interrupting systemthat is not only efficient and reliable, but also inexpensive tomanufacture, install and operate.

Another object of my invention is to provide a circuit-interruptingsystem in which the current fiow shall be diverted before the contactsare sufiiciently opened to produce a substantial arc therebetween.

According to my invention, I provide a system incorporating an electricdischarge device provided with a plurality ofprincipal electrodes and aplurality of control or starting electrodes. The discharge device isconnected across a set of main contact members of a switching device.The discharge device is of the arc-like discharge type, and itsoperating characteristic is such that for the proper control potentialonly a relatively small potential across the principal electrodes isrequired to initiate a discharge therebetween. The difference inpotential between the principal electrodes after a discharge is thusinitiated is substantially smaller than the drop in potential across themain contact members of the switching device. Therefore, when adischarge is produced between the principal electrodes, current ceasesto iiow through the main contact memhere.

In the practice of my invention, the principal electrodes of thedischarge device are connected directly across the main contact memberswhere the arcing is to be eliminated. The starting electrodes areconnected to a source of potential havihg a predetermined phase relationwith the potential impressed upon the principal electrodes. Controlmeans cooperatively associated with means for actuating the switchingdevice or main contact mechanism are utilized to control theenergization of the starting electrodes a predetermined time before themain contacts open.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and its method ofoperation, together with additional objects and advantages thereof, willbest be understood from the following description of spe cificembodiments, when read in connection with the accompanying drawings, inwhich:

Figure 1 is a diagrammatic view showing an embodiment of my invention;and

Figs. 2, 3 and 4 are diagrammatic views showing modifications of myinvention.

The apparatus shown in Figure 1 comprises a plurality of supply lines ormain conductors ll and it A main line switching device or main 5 contactmechanism i5 is connected in the con ductor ii. The contact mechanism 95comprises a pair of stationary contact members it, a cooperating movablecontact member 39, a spring biased toggle mechanism ii, anelectromagnetic tripping mechanism 23 and a trip coil 25. The contactmechanism it may be of any conventional type, as the specific structureshown forms no part of the present invention.

An electric discharge device 211 is connected in w the conductor ll inparallel with the contact mechanism it. The discharge device 2? ispreferably of the immersed ignition electrode type and is provided witha pair of mercury pool electrodes 2t and 3!. In the mercury electrodes'29 and suitable starting or ignition electrodes 33 and 35,respectively, are dipped for providing a cathode spot at the desiredtime. A transformer 37 having a primary winding 39 andsecondary windingsii and d3 is provided for energizing the starting electrodes 33 and 35.A rectifier 45 may be provided so that current will flow throughstarting electrode 33 when the electrode 29 is negative with respect tothe electrode 3i. Similarly, a rectifier ll may be provided so thatcurrent will flow through starting electrode when electrode ii isnegative with respect to electrode 33. The rectifiers i5 and M are shownas disc or oxide film rectiflers, but it will be understood thatthermionic or electric'discharge devices may be utilized. The circuitfor starting electrode 33 ex- 35 tends from one end of secondary winding4|, through rectifier 65, starting electrode 33, electrode 29 to theother end of secondary winding 4 I. The circuit for starting electrode35 extends from one end of secondary winding it through the rectifierii, starting electrode 35, electrode 3| to the other end of secondarywinding 63.

To control theenergization of the transformer 3'! and thus the startingelectrodes 29 and 3i, an electro-magnetic device 49 having a set ofcontact members 5i and an operating coil 531s provided. The circuit forthe primary winding 39 extends from main conductor it through thecontacts 5|, primary winding 39 to the main conductor I3. 50 However, itwill be understood that the primary winding 39 may be energized from anysuitable source of electrical energy having the proper phase relation tothe main conductors H and l3.

A current transformer 55, the primary winding thereof being indicated asconductor II, is connected in series with the main contact mechanism I5and in parallel with the discharge device 21. A secondary winding 51 ofcurrent transformer 55 is adapted to energize operating coil 53 and tripcoil 25 in relation to the current flowing through the contact membersI1 and I9 of the main contact mechanism I5. The operating coil 53 isselected so it will actuate electromagnetic device 49 when the currentflowing through the contact mechanism I5 is slightly less than thatrequired to cause trip coil 25 to actuate the tripping mechanism 23.

The operation of the above-described apparatus may be set forth asfollows: Assume that the contact mechanism I5 is in the closed-circuitposition with the movable member I9 in engagement with the stationarycontact members I1 and that normal current traverses the conductor II,contact members I1 and I9 and conductor I3. When an overload orshort-circuit occurs, the current through the primary winding of currenttransformer 55 and the contact members I1 and I9 increases, thusincreasing the current through operating coil 53 and trip coil 25. Whenthe current increases to a first predetermined value, the operating coil53 actuates the electromagnetic device 49 to close contacts 5 I, therebyenergizing the primary winding 39 of transformer 31. Current is nowtransmitted from secondary winding 4I through starting electrode 33 toform a cathode spot on mercury electrode 29. Similarly, currenttransmitted from secondary winding 43 through starting electrodes 35forms a cathode spot on mercury electrode 3|. Current does not flowthrough the discharge device 21 when the contact mechanism I5 is closed,because the electrodes 29 and 3| are at substantially the samepotential.

When the current through current transformer 55 reaches a secondpredetermined value, slightly higher than the first predetermined value,thetrip coil 25 actuates the trippingmechanism 23, thus causing the maincontact mechanism to open. The coils 53 and 25 may be energizedsubstantially simultaneously if the inertias of the moving parts of theelectromagnetic device 49 and the contact mechanism I5 are such that thetransformer 31 is energized before the main contact members begin toopen. When the contact members I1 and I9 separate a short distance, thedifference in potential increases between the electrodes 29 and 3| byreason of the increase in the contact resistance and the dischargedevice 21 becomes energized. The contact resistance is substantialbefore the contacts are entirely separated and, therefore, the dischargedevice becomes conductive before an arc is produced between thecontacts. The current in conductor I I is then shunted around thecurrent transformer 55 and the contact-members I1 and I9 through thedischarge device 21. When the discharge device becomes energized, themagnitude of the potential drop between the electrodes 29 and 3| and,therefore, between contact members I1 and I9 is such that the currentflow can no longer be maintained through the contact members I1 and I9.Current transformer 55 then becomes deenergized, and thus the operatingcoil 53 and trip coil 25 become deenergized. Upon deenergization ofoperating coil 53, electromagnetic device 49 is actuated to opencontacts 5|, thereby deenergizing the. starting electrodes 33 and 35.Current in conductor I I continues to flow through discharge device 21until the end of the half cycle of the alternating current. Thedischarge device thus becomes deenergized, and is not reignited in thesucceeding half cycles because the starting electrodes 33 and 35 aredeenergized.

In Fig. 2, a pair of electric discharge devices 59 and GI, each havingan anode 53, a cathode 35 and a starting electrode 61 are connected inparallel to" the main contact mechanism I5. Gridcontrolled gaseousdevices and other arc-like discharge devices may be utilized in place ofthe discharge devices 59 and 6|. The discharge devices ,59 and 6| areconnected in anti-parallel so that the anode-cathode polarity of one ofthem always corresponds to the polarity of the alternating current inconductor l I. The starting electrodes 61 of discharge devices 59 and GIare energized from transformers 69 and H, respectively. The transformersmay be energized from a circuit supplied by a feeder or controltransformer 13 through a phase shifter 14. The potential impressed uponthe starting electrode 61 may be dephased by phase shifter 14 so that itreaches a positive value of substantial magnitude at the beginning ofeach positive half cycle of potential impressed upon the main electrode63. The operation of the system is similar to that hereinabove describedwith reference to Fig. 1. When the potential across the main contactmechanism increases, the discharged device forwhich the anode-cathodepotential is of proper polarity is immediately energized and then thecircuit is completely interrupted.

As is apparent from Fig. 2, the circuit may be opened if only one of thedischarge devices 59 and BI is utilized. If this is desirable, thedischarge device 5|, transformer H and rectifier 41 may be omitted.

In Fig. 3, a transformer 15, having a primary winding 11 and a singlesecondary winding 19, is utilized to energize both of the startingelectrodes 33 and 35. An additional set of contacts H on electromagneticdevice 49 is provided to control the energization of the startingelectrodes 33 and 35. A current limiting resistor 33 may also beprovided. The circuit for the starting electrodes 33 and 35 extends fromone side of secondary winding 19 through resistor 83, starting electrode35, electrode 3I, conductor II, contact members I1 and I9, conductor II,electrode 29, starting electrode 33, contacts 8| to the other side ofsecondary winding 19. The operation of the system is similar to thathereinabove described with reference to Fig. 1. When the main contactmechanism I5 is opened, the potential across the contact members I1 andI9 is also impressed upon the starting electrode circuit through theelectrodes 29 and 3 I. To deenergize the discharge device 21 after thecontact mechanism I5 has been opened, the starting electrode circuit isopened when electromagnetic device 49 is actuated to open contacts 8 I.

It will readily be understood that the actuation of main contactmechanism I5 may be initiated by means other than the current responsivemeans hereinabove described. In Fig. 4, the energization of operatingcoil 53 and trip coil 25 is mitiated by completing the circuit through aset of contacts 85. The contacts may be cooperatively associated with amanually operable device, such as a push buttoncr knife switch, or withan electromagnetic device actuated in response to predetermined circuitconditions. A pair of conductors 81 and 89, energized from a source ofelectrical energy (not shown) are utilized for energizing the coils 53and 25. When contact membars 85 are closed, operating coil 53 becomesenergized through a circuit which extends from conductor 81 throughcontacts 85, operating coil 53, resistor 9| to conductor 89. The device452 is actuated to close a plurality of contacts 5|, to energize thestarting electrodes 33 and 35 from batteries 93 and 95, respectively, orany other suitable source of unidirectional current. Contacts 91 areclosed to establish a holding circuit for the operating coil 53. Contactmembers 99 are also closed to energize trip coil 25 to cause theactuation of contact mechanism I5. The discharge device 21 becomesenergized and the current in conductor II is shunted around contactmembers I1 and I9 through the device 21 as hereinabove described. A setof contacts l0] actuated by con tact mechanism l5 are utilized todeenergize operating coil 53 when the contact members 11 and [9 areopened. The starting electrodes 33 and 35 are then deenergized by theopening of contacts 5| and the discharge device 21 becomes deenergizedat the end of the half cycle of the alternat-' ing current.

I do not wish to be restricted to the specific structural details,arrangement of parts or circuit connections herein set forth as variousother modifications thereof may be effected without departing from thespirit and scope of my invention. I desire, therefore, that only suchlimitations shall be imposed as are indicated in the appended claims.

I claim as my invention:

1. A circuit-interrupting system comprising a main contact mechanism, anelectric discharge device connected in parallel with the said contactmechanism, the said device having two main electrodes and a startingelectrode associated with each main electrode, and means responsive to apredetermined current through the said contact mechanism for energizingat least one of the said starting electrodes a predetermined time beforethe said contact mechanism is actuated.

2. A circuit-interrupting system comprising a main contact mechanism, anelectric discharge device connected in parallel with the said contactmechanism, the said device having two main electrodes and a startingelectrode associated with each main electrode, and means responsive to apredetermined current through the said contact main electrode, and meansresponsive to a predetermined current through the said contact membersfor alternately energizing said startingelectrodes a predetermined timebefore the said contact mechanism is actuated.

4. A circuit-interrupting system comprising a main contact mechanism, anelectric discharge device connected in parallel with the said contactmechanism, the said device having two main electrodes and astarting-electrode associated with each main electrode, and means forenergizing at least one of the said starting-electrodes a predeterminedtime before the said contact mechanism is actuated.

5. A circuit-interrupting system comprising a main contact mechanism, apair of separate electric discharge devices connected in anti-parallelacross the contact mechanism, each ofsaid devices having a plurality ofprincipal electrodes and an ignition-electrode cooperatively associatedwith one of the said principal electrodes, and means responsive to apredetermined current through the said contact mechanism for energizingthe said ignition electrodes a predetermined time before the saidcontact mechanism is actuated. e

6. A circuit-interrupting system comprising a main contact mechanism, anelectric discharge device connected in parallel with the said contactmechanism, the said device having a plurality of principal electrodesand a starting electrode 00- operatively associated with one of the saidprincipal electrodes, and means for energizing the said ignitionelectrode before the said contact mechanism is actuated.

7. In, a circuit-interrupting system for an electrical circuitcomprising a main contact mechanism connected in parallel with anelectric discharge device having a starting electrode and a plurality ofprincipal electrodes, means for actuating the said contact mechanism,and starting means cooperatively associated with the said actuatingmeans for impressing a potential between the said starting electrode andone of the said principal electrodes before the said contact mechanismis actuated.

8. In a circuit-interrupting system for an electrical circuit comprisinga main contact mechanism connected in parallel with an electricdischarge device having a starting electrode and a plurality ofprincipal electrodes, means for actuating the said main contactmechanism, starting means cooperatively associated with the saidactuating means for impressing a potential beand a control electrode,and means for energizing the said control electrodes before the contactmechanism is actuated.

10. A circuit interrupting system comprising a main contact mechanism, apair of separate electric discharge devices connected in anti-parallelacross the said contact mechanism, each of said devices having aplurality of principal electrodes and a control electrode, means foractuating the said contact mechanism, means associated with the saidactuating means for impressing a potential between the control electrodeand one of the said principal electrodes of each of said dischargedevices before the said contact mecha-' nism is actuated, and means fordeenergizing the said discharge devices, after the said contactmechanism has been actuated.

11. A circuit-interrupting system comprising a main contact mechanism,an electric discharge device connected in parallel with the said,contact mechanism, the said device having two main electrodes and acontrol electrode associated with each main electrode, and meansresponsive to a predetermined circuit condition for energizing the saidcontrol electrodes before the said contact mechanism is actuated.

12. For use in opening a circuit, the combination comprising mechanicalcontacts in said circuit for opening said circuit, normallynon-conductive electric discharge valve means bridging said contacts,means for opening said contacts, the said valve means having controlelectrode means which is energized sufliciently to render the valvemeans conductive in response to the excitation of said opening meansprior to the actuation of said contacts by said opening means, and meanscooperative with said contacts as they are opening for rendering saidvalve means conductive before an arc is formed between said contacts.

13. A circuit'interrupting system comprising a main contact mechanism,an electric discharge device of the immersed-ignition-electrode typeconnected in parallel with the said contact mechanism, the said devicehaving a plurality of principal electrodes and a starting electrodecooperatively associated with each of said principal electrodes, andmeans for energizing at least one of said starting electrodes before thesaid contact mechanism is actuated.

14. A circuit interrupting system comprising a main contact mechanism, apair of separate elec tric discharge devices of theimmersed-ignitionelectrode type connected in anti-parallel across thesaid contact mechanism, each of said devices having an anode, a cathodeof the mercury type, and an ignition electrode immersed in said cathode,a rectifier connected to each of said ignition electrodes, means foractuating said contact mechanism, means including a transformerassociated with said actuating means for impressing a potential throughsaid rectifier between said starting electrode and said cathode of eachof said discharge devices before the contact mechaelectrodes, means foractuating said contact mechanism, means for energizing said dischargedevices, said energizing means including a transformer associated withsaid actuating means for impressing a potential through said rectifierbetween said starting electrode and said cathode of each of saiddischarge devices before the contact mechanism is actuated, and meansfor deenergizing said discharge devices, after said contact mechanismhas been actuated.

' CHARLES P. WEST.

